1. Field of the Invention
The present invention relates to an oil pressure control apparatus of a vehicle power transmission apparatus.
2. Description of the Related Art
As a power transmission apparatus provided in a vehicle, a power transmission apparatus is known that has a belt-driven continuously variable transmission in which a belt is clamped with oil pressure to transmit motive power, and a gear ratio is changed by changing a belt contact radius, and a hydraulic lockup clutch that is provided in a hydrodynamic motive power transmission apparatus provided in a motive power transmission path and directly couples a motive power source side and the belt-driven continuously variable transmission side.
In an oil pressure control apparatus of this sort of vehicle power transmission apparatus, many control valves of various types, electromagnetic valves that control those control valves, and the like are provided. For example, a line oil pressure control valve that regulates a line oil pressure that becomes the source pressure for the oil pressure of various parts; a gearshift oil pressure control valve that regulates the line oil pressure that becomes the source pressure, and supplies a gearshift oil pressure that controls the gear ratio of the belt-driven continuously variable transmission to a driving-side pulley (primary pulley) of the belt-driven continuously variable transmission; a clamping oil pressure control valve that likewise regulates the line oil pressure that becomes the source pressure, and supplies a clamping oil pressure that controls belt clamping pressure of the belt-driven continuously variable transmission to a driven-side pulley (secondary pulley) of the belt-driven continuously variable transmission; a lockup control valve that performs switching when controlling engagement/release of the lockup clutch; and the like are provided. Also provided are linear electromagnetic valves, ON-OFF electromagnetic valves, or the like for controlling each of these control valves.
Conventionally, control of the line oil pressure control valve and control of the lockup control valve are performed with one linear electromagnetic valve, by supplying a control oil pressure of the one linear electromagnetic valve to the line oil pressure control valve and the lockup control valve. In this case, by switching an oil path according to engagement/release of the lockup clutch, the control oil pressure of the linear electromagnetic valve is supplied to either one of the line oil pressure control valve and the lockup control valve. JP 2000-130574A discloses technology in which only control of the line oil pressure control valve is performed with a single linear electromagnetic valve.
Incidentally, when a configuration is adopted in which an oil path is switched according to engagement/release of a lockup clutch as described above, it is necessary to provide a dedicated ON-OFF electromagnetic valve for switching that oil path. That is, separate electromagnetic valves are necessary for switching between control of the line oil pressure control valve and control of the lockup control valve. As a result, there is the problem that such a configuration leads to increased cost and size of the apparatus.